On Dec 12, 2006, at 5:54 PM, Cory Papenfuss wrote: > Umm... sorry. I'll have to throw the "bullshit flag" on that > play. If one measures and analog voltage at 22-bits, does nothing > to it, > and then throws away the least-significant 10 bits to produce 12- > bits, the > results are absolutely identical to another who quantizes at 12- > bits to > begin with. Only if "mid-processing" (i.e. processing between the > data > measurement and RAW file writing) is done is there a difference. That > "mid-processing" is precisely the unknown that I'm talking about, > but one > would assume that some was done.
I didn't say no processing was done. You did. It was stated in one of the interviews with the engineers that Ken translated that they took opportunities to do signal processing due to the 22bit A-D that were not otherwise feasible. >> I don't presume to know what Pentax did in tuning the A->D converter >> and subsequent 22->12 bit transformation, but whatever the body >> writes to the RAW format file as sensor date is, by definition, the >> camera's RAW format data. >> > Yes, but no longer presumed to be an unaltered digitized version > of exactly what the sensor sees. It never has been. Transformations occur between photosite and digital representation in all cases that I'm aware of ... that's what all the custom signal processing chips in these cameras are all about, in part at least. > >> You can't get at or use anything more anyway so there's no point in >> debating it. >> > If you get the white-balance wrong, you only get 10 or 11 (linear) > bits of the red channel in the example I proposed above. That does > make a > difference. > > For the most part, this is speculation since nobody but the > image-processing software guys at Pentax know for sure. I'm just > saying > that not only is what I'm suggesting possible, it's rather *likely* > given > that they're trying to exploit the additional data available. But as I said above, the whole concern is nonsensical and pure speculation because you only get the RAW data the camera writes anyway. And the little working with the K10D that I have done so far indicates pretty clearly that it has exceptionally good image quality, even compared with the *ist DS which also has very very good image quality. The K10D has "better" 12 bit RAW data, in other words. I think that it is in part due to the 22bit A-D and whatever data massaging they do in that space, at least in part. If you want to continue to speculate for no particular reason, well, be my guest. Godfrey -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
